branch-2.0.4-alpha/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlocksWithNotEnoughRacks.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hdfs.server.blockmanagement;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import java.util.ArrayList;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.impl.Log4JLogger;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.BlockLocation;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.DFSTestUtil;
import org.apache.hadoop.hdfs.HdfsConfiguration;
import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.apache.hadoop.hdfs.protocol.DatanodeID;
import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
import org.apache.hadoop.hdfs.server.datanode.DataNode;
import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
import org.apache.hadoop.hdfs.server.namenode.NameNodeAdapter;
import org.apache.log4j.Level;
import org.junit.Test;

public class TestBlocksWithNotEnoughRacks {
  public static final Log LOG = LogFactory.getLog(TestBlocksWithNotEnoughRacks.class);
  static {
    ((Log4JLogger)LogFactory.getLog(FSNamesystem.class)).getLogger().setLevel(Level.ALL);
    ((Log4JLogger)LOG).getLogger().setLevel(Level.ALL);
  }

  /*
   * Return a configuration object with low timeouts for testing and 
   * a topology script set (which enables rack awareness).  
   */
  private Configuration getConf() {
    Configuration conf = new HdfsConfiguration();

    // Lower the heart beat interval so the NN quickly learns of dead
    // or decommissioned DNs and the NN issues replication and invalidation
    // commands quickly (as replies to heartbeats)
    conf.setLong(DFSConfigKeys.DFS_HEARTBEAT_INTERVAL_KEY, 1L);

    // Have the NN ReplicationMonitor compute the replication and
    // invalidation commands to send DNs every second.
    conf.setInt(DFSConfigKeys.DFS_NAMENODE_REPLICATION_INTERVAL_KEY, 1);

    // Have the NN check for pending replications every second so it
    // quickly schedules additional replicas as they are identified.
    conf.setInt(DFSConfigKeys.DFS_NAMENODE_REPLICATION_PENDING_TIMEOUT_SEC_KEY, 1);

    // The DNs report blocks every second.
    conf.setLong(DFSConfigKeys.DFS_BLOCKREPORT_INTERVAL_MSEC_KEY, 1000L);

    // Indicates we have multiple racks
    conf.set(DFSConfigKeys.NET_TOPOLOGY_SCRIPT_FILE_NAME_KEY, "xyz");
    return conf;
  }

  /*
   * Creates a block with all datanodes on the same rack, though the block
   * is sufficiently replicated. Adds an additional datanode on a new rack. 
   * The block should be replicated to the new rack.
   */
  @Test
  public void testSufficientlyReplBlocksUsesNewRack() throws Exception {
    Configuration conf = getConf();
    final short REPLICATION_FACTOR = 3;
    final Path filePath = new Path("/testFile");
    // All datanodes are on the same rack
    String racks[] = {"/rack1", "/rack1", "/rack1"};
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
      .numDataNodes(racks.length).racks(racks).build();

    try {
      // Create a file with one block with a replication factor of 3
      final FileSystem fs = cluster.getFileSystem();
      DFSTestUtil.createFile(fs, filePath, 1L, REPLICATION_FACTOR, 1L);
      ExtendedBlock b = DFSTestUtil.getFirstBlock(fs, filePath);
      DFSTestUtil.waitForReplication(cluster, b, 1, REPLICATION_FACTOR, 0);

      // Add a new datanode on a different rack
      String newRacks[] = {"/rack2"};
      cluster.startDataNodes(conf, 1, true, null, newRacks);
      cluster.waitActive();

      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);
    } finally {
      cluster.shutdown();
    }
  }

  /*
   * Like the previous test but the block starts with a single replica,
   * and therefore unlike the previous test the block does not start
   * off needing replicas.
   */
  @Test
  public void testSufficientlySingleReplBlockUsesNewRack() throws Exception {
    Configuration conf = getConf();
    short REPLICATION_FACTOR = 1;
    final Path filePath = new Path("/testFile");

    String racks[] = {"/rack1", "/rack1", "/rack1", "/rack2"};
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
      .numDataNodes(racks.length).racks(racks).build();
    final FSNamesystem ns = cluster.getNameNode().getNamesystem();

    try {
      // Create a file with one block with a replication factor of 1
      final FileSystem fs = cluster.getFileSystem();
      DFSTestUtil.createFile(fs, filePath, 1L, REPLICATION_FACTOR, 1L);
      ExtendedBlock b = DFSTestUtil.getFirstBlock(fs, filePath);
      DFSTestUtil.waitForReplication(cluster, b, 1, REPLICATION_FACTOR, 0);

      REPLICATION_FACTOR = 2;
      NameNodeAdapter.setReplication(ns, "/testFile", REPLICATION_FACTOR);
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);
    } finally {
      cluster.shutdown();
    }
  }

  /*
   * Creates a block with all datanodes on the same rack. Add additional
   * datanodes on a different rack and increase the replication factor, 
   * making sure there are enough replicas across racks. If the previous
   * test passes this one should too, however this test may pass when
   * the previous one fails because the replication code is explicitly
   * triggered by setting the replication factor.
   */
  @Test
  public void testUnderReplicatedUsesNewRacks() throws Exception {
    Configuration conf = getConf();
    short REPLICATION_FACTOR = 3;
    final Path filePath = new Path("/testFile");
    // All datanodes are on the same rack
    String racks[] = {"/rack1", "/rack1", "/rack1", "/rack1", "/rack1"};
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
      .numDataNodes(racks.length).racks(racks).build();
    final FSNamesystem ns = cluster.getNameNode().getNamesystem();

    try {
      // Create a file with one block
      final FileSystem fs = cluster.getFileSystem();
      DFSTestUtil.createFile(fs, filePath, 1L, REPLICATION_FACTOR, 1L);
      ExtendedBlock b = DFSTestUtil.getFirstBlock(fs, filePath);
      DFSTestUtil.waitForReplication(cluster, b, 1, REPLICATION_FACTOR, 0);
      
      // Add new datanodes on a different rack and increase the
      // replication factor so the block is underreplicated and make
      // sure at least one of the hosts on the new rack is used. 
      String newRacks[] = {"/rack2", "/rack2"};
      cluster.startDataNodes(conf, 2, true, null, newRacks);
      REPLICATION_FACTOR = 5;
      NameNodeAdapter.setReplication(ns, "/testFile", REPLICATION_FACTOR);

      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);
    } finally {
      cluster.shutdown();
    }
  }

  /*
   * Test that a block that is re-replicated because one of its replicas
   * is found to be corrupt and is re-replicated across racks.
   */
  @Test
  public void testCorruptBlockRereplicatedAcrossRacks() throws Exception {
    Configuration conf = getConf();
    short REPLICATION_FACTOR = 2;
    int fileLen = 512;
    final Path filePath = new Path("/testFile");
    // Datanodes are spread across two racks
    String racks[] = {"/rack1", "/rack1", "/rack2", "/rack2"};
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
      .numDataNodes(racks.length).racks(racks).build();
    final FSNamesystem ns = cluster.getNameNode().getNamesystem();

    try {
      // Create a file with one block with a replication factor of 2
      final FileSystem fs = cluster.getFileSystem();
      
      DFSTestUtil.createFile(fs, filePath, fileLen, REPLICATION_FACTOR, 1L);
      final String fileContent = DFSTestUtil.readFile(fs, filePath);

      ExtendedBlock b = DFSTestUtil.getFirstBlock(fs, filePath);
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);

      // Corrupt a replica of the block
      int dnToCorrupt = DFSTestUtil.firstDnWithBlock(cluster, b);
      assertTrue(MiniDFSCluster.corruptReplica(dnToCorrupt, b));

      // Restart the datanode so blocks are re-scanned, and the corrupt
      // block is detected.
      cluster.restartDataNode(dnToCorrupt);

      // Wait for the namenode to notice the corrupt replica
      DFSTestUtil.waitCorruptReplicas(fs, ns, filePath, b, 1);

      // The rack policy is still respected
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);

      // Ensure all replicas are valid (the corrupt replica may not
      // have been cleaned up yet).
      for (int i = 0; i < racks.length; i++) {
        String blockContent = cluster.readBlockOnDataNode(i, b);
        if (blockContent != null && i != dnToCorrupt) {
          assertEquals("Corrupt replica", fileContent, blockContent);
        }
      }
    } finally {
      cluster.shutdown();
    }
  }

  /*
   * Reduce the replication factor of a file, making sure that the only
   * cross rack replica is not removed when deleting replicas.
   */
  @Test
  public void testReduceReplFactorRespectsRackPolicy() throws Exception {
    Configuration conf = getConf();
    short REPLICATION_FACTOR = 3;
    final Path filePath = new Path("/testFile");
    String racks[] = {"/rack1", "/rack1", "/rack2", "/rack2"};
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
      .numDataNodes(racks.length).racks(racks).build();
    final FSNamesystem ns = cluster.getNameNode().getNamesystem();

    try {
      // Create a file with one block
      final FileSystem fs = cluster.getFileSystem();
      DFSTestUtil.createFile(fs, filePath, 1L, REPLICATION_FACTOR, 1L);
      ExtendedBlock b = DFSTestUtil.getFirstBlock(fs, filePath);
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);

      // Decrease the replication factor, make sure the deleted replica
      // was not the one that lived on the rack with only one replica,
      // ie we should still have 2 racks after reducing the repl factor.
      REPLICATION_FACTOR = 2;
      NameNodeAdapter.setReplication(ns, "/testFile", REPLICATION_FACTOR); 

      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);
    } finally {
      cluster.shutdown();
    }
  }

  /*
   * Test that when a block is replicated because a replica is lost due
   * to host failure the the rack policy is preserved.
   */
  @Test
  public void testReplDueToNodeFailRespectsRackPolicy() throws Exception {
    Configuration conf = getConf();
    short REPLICATION_FACTOR = 3;
    final Path filePath = new Path("/testFile");
    // Last datanode is on a different rack
    String racks[] = {"/rack1", "/rack1", "/rack1", "/rack2", "/rack2"};
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
      .numDataNodes(racks.length).racks(racks).build();
    final FSNamesystem ns = cluster.getNameNode().getNamesystem();
    final DatanodeManager dm = ns.getBlockManager().getDatanodeManager();

    try {
      // Create a file with one block with a replication factor of 2
      final FileSystem fs = cluster.getFileSystem();
      DFSTestUtil.createFile(fs, filePath, 1L, REPLICATION_FACTOR, 1L);
      ExtendedBlock b = DFSTestUtil.getFirstBlock(fs, filePath);
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);

      // Make the last datanode look like it failed to heartbeat by 
      // calling removeDatanode and stopping it.
      ArrayList<DataNode> datanodes = cluster.getDataNodes();
      int idx = datanodes.size() - 1;
      DataNode dataNode = datanodes.get(idx);
      DatanodeID dnId = dataNode.getDatanodeId();
      cluster.stopDataNode(idx);
      dm.removeDatanode(dnId);

      // The block should still have sufficient # replicas, across racks.
      // The last node may not have contained a replica, but if it did
      // it should have been replicated within the same rack.
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);
      
      // Fail the last datanode again, it's also on rack2 so there is
      // only 1 rack for all the replicas
      datanodes = cluster.getDataNodes();
      idx = datanodes.size() - 1;
      dataNode = datanodes.get(idx);
      dnId = dataNode.getDatanodeId();
      cluster.stopDataNode(idx);
      dm.removeDatanode(dnId);

      // Make sure we have enough live replicas even though we are
      // short one rack and therefore need one replica
      DFSTestUtil.waitForReplication(cluster, b, 1, REPLICATION_FACTOR, 1);
    } finally {
      cluster.shutdown();
    }
  }
  
  /*
   * Test that when the excess replicas of a block are reduced due to
   * a node re-joining the cluster the rack policy is not violated.
   */
  @Test
  public void testReduceReplFactorDueToRejoinRespectsRackPolicy() 
      throws Exception {
    Configuration conf = getConf();
    short REPLICATION_FACTOR = 2;
    final Path filePath = new Path("/testFile");
    // Last datanode is on a different rack
    String racks[] = {"/rack1", "/rack1", "/rack2"};
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
      .numDataNodes(racks.length).racks(racks).build();
    final FSNamesystem ns = cluster.getNameNode().getNamesystem();
    final DatanodeManager dm = ns.getBlockManager().getDatanodeManager();

    try {
      // Create a file with one block
      final FileSystem fs = cluster.getFileSystem();
      DFSTestUtil.createFile(fs, filePath, 1L, REPLICATION_FACTOR, 1L);
      ExtendedBlock b = DFSTestUtil.getFirstBlock(fs, filePath);
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);

      // Make the last (cross rack) datanode look like it failed
      // to heartbeat by stopping it and calling removeDatanode.
      ArrayList<DataNode> datanodes = cluster.getDataNodes();
      assertEquals(3, datanodes.size());
      DataNode dataNode = datanodes.get(2);
      DatanodeID dnId = dataNode.getDatanodeId();
      cluster.stopDataNode(2);
      dm.removeDatanode(dnId);

      // The block gets re-replicated to another datanode so it has a 
      // sufficient # replicas, but not across racks, so there should
      // be 1 rack, and 1 needed replica (even though there are 2 hosts 
      // available and only 2 replicas required).
      DFSTestUtil.waitForReplication(cluster, b, 1, REPLICATION_FACTOR, 1);

      // Start the "failed" datanode, which has a replica so the block is
      // now over-replicated and therefore a replica should be removed but
      // not on the restarted datanode as that would violate the rack policy.
      String rack2[] = {"/rack2"};
      cluster.startDataNodes(conf, 1, true, null, rack2);
      cluster.waitActive();      
      
      // The block now has sufficient # replicas, across racks
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);
    } finally {
      cluster.shutdown();
    }
  }

  /*
   * Test that rack policy is still respected when blocks are replicated
   * due to node decommissioning.
   */
  @Test
  public void testNodeDecomissionRespectsRackPolicy() throws Exception {
    Configuration conf = getConf();
    short REPLICATION_FACTOR = 2;
    final Path filePath = new Path("/testFile");

    // Configure an excludes file
    FileSystem localFileSys = FileSystem.getLocal(conf);
    Path workingDir = localFileSys.getWorkingDirectory();
    Path dir = new Path(workingDir, "build/test/data/temp/decommission");
    Path excludeFile = new Path(dir, "exclude");
    Path includeFile = new Path(dir, "include");
    assertTrue(localFileSys.mkdirs(dir));
    DFSTestUtil.writeFile(localFileSys, excludeFile, "");
    DFSTestUtil.writeFile(localFileSys, includeFile, "");
    conf.set(DFSConfigKeys.DFS_HOSTS_EXCLUDE, excludeFile.toUri().getPath());
    conf.set(DFSConfigKeys.DFS_HOSTS, includeFile.toUri().getPath());

    // Two blocks and four racks
    String racks[] = {"/rack1", "/rack1", "/rack2", "/rack2"};
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
      .numDataNodes(racks.length).racks(racks).build();
    final FSNamesystem ns = cluster.getNameNode().getNamesystem();

    try {
      // Create a file with one block
      final FileSystem fs = cluster.getFileSystem();
      DFSTestUtil.createFile(fs, filePath, 1L, REPLICATION_FACTOR, 1L);
      ExtendedBlock b = DFSTestUtil.getFirstBlock(fs, filePath);
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);

      // Decommission one of the hosts with the block, this should cause 
      // the block to get replicated to another host on the same rack,
      // otherwise the rack policy is violated.
      BlockLocation locs[] = fs.getFileBlockLocations(
          fs.getFileStatus(filePath), 0, Long.MAX_VALUE);
      String name = locs[0].getNames()[0];
      DFSTestUtil.writeFile(localFileSys, excludeFile, name);
      ns.getBlockManager().getDatanodeManager().refreshNodes(conf);
      DFSTestUtil.waitForDecommission(fs, name);

      // Check the block still has sufficient # replicas across racks
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);
    } finally {
      cluster.shutdown();
    }
  }

  /*
   * Test that rack policy is still respected when blocks are replicated
   * due to node decommissioning, when the blocks are over-replicated.
   */
  @Test
  public void testNodeDecomissionWithOverreplicationRespectsRackPolicy() 
      throws Exception {
    Configuration conf = getConf();
    short REPLICATION_FACTOR = 5;
    final Path filePath = new Path("/testFile");

    // Configure an excludes file
    FileSystem localFileSys = FileSystem.getLocal(conf);
    Path workingDir = localFileSys.getWorkingDirectory();
    Path dir = new Path(workingDir, "build/test/data/temp/decommission");
    Path excludeFile = new Path(dir, "exclude");
    Path includeFile = new Path(dir, "include");
    assertTrue(localFileSys.mkdirs(dir));
    DFSTestUtil.writeFile(localFileSys, excludeFile, "");
    DFSTestUtil.writeFile(localFileSys, includeFile, "");
    conf.set(DFSConfigKeys.DFS_HOSTS, includeFile.toUri().getPath());
    conf.set(DFSConfigKeys.DFS_HOSTS_EXCLUDE, excludeFile.toUri().getPath());

    // All hosts are on two racks, only one host on /rack2
    String racks[] = {"/rack1", "/rack2", "/rack1", "/rack1", "/rack1"};
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
      .numDataNodes(racks.length).racks(racks).build();
    final FSNamesystem ns = cluster.getNameNode().getNamesystem();

    try {
      final FileSystem fs = cluster.getFileSystem();
      DFSTestUtil.createFile(fs, filePath, 1L, REPLICATION_FACTOR, 1L);
      ExtendedBlock b = DFSTestUtil.getFirstBlock(fs, filePath);
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);

      // Lower the replication factor so the blocks are over replicated
      REPLICATION_FACTOR = 2;
      fs.setReplication(filePath, REPLICATION_FACTOR);

      // Decommission one of the hosts with the block that is not on
      // the lone host on rack2 (if we decomission that host it would
      // be impossible to respect the rack policy).
      BlockLocation locs[] = fs.getFileBlockLocations(
          fs.getFileStatus(filePath), 0, Long.MAX_VALUE);
      for (String top : locs[0].getTopologyPaths()) {
        if (!top.startsWith("/rack2")) {
          String name = top.substring("/rack1".length()+1);
          DFSTestUtil.writeFile(localFileSys, excludeFile, name);
          ns.getBlockManager().getDatanodeManager().refreshNodes(conf);
          DFSTestUtil.waitForDecommission(fs, name);
          break;
        }
      }

      // Check the block still has sufficient # replicas across racks,
      // ie we didn't remove the replica on the host on /rack1.
      DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);
    } finally {
      cluster.shutdown();
    }
  }
}